1. To weaken or deprive of strength or vitality: This is the most common meaning.
* Example: The long journey enervated the travelers.
* Synonyms: weaken, debilitate, sap, exhaust, drain
2. To give strength or vigor to: This meaning is less common but still exists.
* Example: The fresh air enervated the hiker.
* Synonyms: invigorate, energize, vitalize, animate
It's important to pay attention to context to determine which meaning is intended.